A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed.
This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also
improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find
practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio
astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna
characteristics

Polychloroprene (neoprene) has been blended with polyvinylchloride (PVC) in different
proportions using a new stabiliser system (magnesium oxide and zinc oxide with
stearic acid) for PVC. The physical properties of the blends show that they can
advantageously replace neoprene in many applications.

Polymer-solvent interaction parameters for the blends of natural rubber (NR) with
styrene-butadiene rubber (SBR) and polybutadiene rubber ( BR) are calculated using
the Flory-Rehner equation by equating the network density of the vulcanizates in
two solvents.

The design, erection and evalution procedures for it microwave anechuic chamber competed at Cochin University for
antenna studies are presented the chamber has an average reflectivity level of - 32 dB on at X-band frequencies, and it i,
comparable to international standards.

Blends of natural rubber (NR) with styrene-butadiene rubber (SBR), polybutadiene
rubber (BR), ethylene-propylene terpolymer (EPDM) and acrylonitrile-butadiene
rubber (NBR) were vulcanised using an efficient vulcanisation (EV) system and a
semi-EV system. Compatible blends show a definite pattern of curing whereas the
incompatible blends show no such pattern.

Pyridoxine-deficient young rats (3 weeks old) had
significantly reduced levels of pituitary TSH, serum
thyroxine (T4) and tri iodothyn nine (T,,) Compared
with pyridoxine-supplemented rats. The status of the
pituitary-thyroid axis of normal, pyridoxine-supplemented
and pyridoxine-deficient rats was evaluated
by studying the binding parameters of [3H](3-nicthylhistidine2)
TRH in the pituitary of these rats. The
effects of TRH and 1'4 injections on pituitary TSH
and serum TSH, T4 and T3 of these two groups were
also compared. The maximal binding of TRH receptors
in the pituitary of pyridoxine-deficient rats was
significantly higher than that of pyridoxine-supplemented
control and normal rats, but there was no change in the binding affinity. Treatment with TRH
stimulated TSH synthesis and release. It also
increased serum T4 and T3 in both pyridoxine-supplemented
and pyridoxine-deficient rats. Treatment with
T4 decreased serum and pituitary TSH in both
pyridoxine-supplemented and pyridoxine-deficient
rats, compared with saline-treated rats. The increased
pituitary TRH receptor content, response to TRH
administration and the fact that regulation at the level
of the pituitary is not affected in the pyridoxinedeficient
rat indicates a hypothalamic origin for the
hypothyroidism of the pyridoxine-deficient rat.

Pyridoxal phosphate (PLP) is the coenzyme of various decarboxylases involved in the
formation of monoamine urotransmitters such as y-aminobulyric acid (GAE3A),
serotonin (5-HT) and dopamine. 1-lowever; in the pyridoxine-deficient rats GABA and
5-HT are decreased in various brain areas including the hypothalamus, with no change
in the catecholamine levels. Serotonin and GABA are known to be involved in blood
pressure control mechanisms. In this study adult Sprague-Dawley rats placed on a
pyridoxine-deficient diet for 8 weeks showed significant hypertension compared with
pyridoxine-supplemented controls. This was associated with a general sympathetic
stimulation. Treatment of deficient rats with a single dose of pyridoxine (10 mg/kg body
weight) reversed the blood pressure to normal levels within 24 h, with concomitant
restoration of hypothalamic 5-HT and GABA, as well as the return of plasma
norepinephrine to nornr;l levels. The results indicate that there is a cause-and-effect
relationship between pyridoxine deficiency and hypertension.

Pyridoxal phosphate is the coenzyme of various decarboxylases involved in the formation
of monoamine neurotransmitters such as y-aminobutyric acid , serotonin , dopamine, and norepinephrine
. Adult male Sprague-Dawley rats placed on a pyridoxine -deficient diet for 8 weeks showed
significant hypertension compared with pyridoxine -supplemented controls . Hypothalamic contents of
pyridoxal phosphate , y-aminobutyric acid, and serotonin in the pyridoxine - deficient rats were significantly
lower than those in pyridoxine -supplemented controls . Hypertension was associated with
sympathetic stimulation . Treatment of pyridoxine-deficient rats with a single dose of pyridoxine (10
mg/kg body weight) reversed the blood pressure to normal levels within 24 hours, with concomitant
restorations of hypothalamic serotonin and y-aminobutyric acid as well as the return of plasma
norepinephrine and epinephrine to normal levels . Also, pyridoxine treatment reversed the hypothalamic
hypothyroidism observed in pyridoxine -deficient rats . These results indicate an association
between pyridoxine deficiency and sympathetic stimulation leading to hypertension.